The present invention relates to composites useful in building structures, such as floor tiles, pavers, blocks, flagstones, concrete bricks, and other architectural products, etc., and methods of making the same.
Most existing processes to polymer coat or glaze Portland cement-based structures use cured Portland cement-based (concrete) structures as inserts or finished components. In other words, prior to polymer coating, glazing or painting masonry on concrete surfaces, concrete structures are in advanced stage of cure, i.e., well aged or heat processed to the point where they are easily handled.
The conventional method of glazing concrete structures is to apply a highly filled polyester or epoxy material on a surface of the structure that is procured by dry casting or extruding a cementitious-based material. In this process, the water to cement ratio (w/c) is minimized by tumbling the aggregates with closely controlled amounts of water and applying pressure to consolidate the damp, vibrated mix even further. These dry cast blocks are often glazed with a thermoset polymer after approximately 24 hours of initial consolidation. Other processes for decorating cured concrete areas include painting with moisture-cured, solvent-based, or air-cured materials, spraying freshly mixed two component systems normally followed by a post cure and xe2x80x9cbroadcastxe2x80x9d whereby freshly mixed unsaturated polyester or epoxy is rolled onto cured concrete floors followed by broadcasting colored sand or colored polymer-coated quartz into the polymer, letting it thermally cure and then sweeping away the excess mineral. Thus, the bonding between the coating and the concrete surface using these conventional processes is basically chemical in nature.
The composite of the present invention has a bond between a thick coating or glaze and a substrate, which is superior in strength to the conventional composites. This bond is not only chemical but is strongly mechanical in nature, consisting of numerous mechanisms, many of which are not available to the above decorative techniques. The present method provides a mechanism for forming a substantially thick transitional layer between a polymeric coating layer and a substrate layer which comprises three dimensional structures (herein alternatively referred to as locks or pockets) that act to mechanically hold the layers together, thereby forming a strong bond between the coating and the substrate which is both chemical and mechanical in nature.
In accordance with the present invention, polymer resin binder blends are combined with solid particle fillers to produce low cost, functional designs on substrates, such as floor tiles, pavers, blocks, and many other building products in limitless colors, styles, and textures for both indoor and outdoor use.
In accordance with one aspect of the present invention, a method is provided for producing a composite structure having a decorative cladding as a first layer affixed to a substrate as a second layer by an intervening transition layer. This method comprises preparing a mixture of a polymerizable resin binder solution and a solid particle filler as the first layer. Placing a cement-based substrate material as the second layer in interfacial relation with the first layer. Developing the transition layer consisting essentially of the binder solution at the interface of the first and second layers, such that binder solution can migrate into the substrate material to form transition layer pockets of binder solution in the substrate material. The binder solution in the first layer and the transition layer is then cured to produce a durable surface cladding mechanically locked and chemically bonded to the second layer.
In accordance with one embodiment of the invention, the binder solution-filler mixture (first layer) is poured into a mold and the substrate material (second layer) is in the form of a cement slurry which is poured over the first layer. The cement slurry is concurrently cured with the resin binder solution to achieve the composite.
According to another embodiment, the substrate material is in the form of a pre-cast concrete structure in tile, paver, block, brick or like form. In this case, the resin binder is preferably curable, both thermally and by exposure to ultraviolet radiation. According to a further embodiment of the invention, the transition layer is applied to a surface of the pre-cast substrate as a precursor step to the application of the first layer. The resin binder solution in the first layer is then exposed to UV radiation. However, due to the UV blocking property of at least some of the filler particles, only a partial UV cure can be achieved. Complete cure of the resin binder in the first layer and in the transition layer is achieved thermally over time.
The invention accordingly comprises a method for making composites that comprised various combinations of steps, all as described hereinafter, and the scope of the invention will be indicated in the claims.